It is advisable to begin a conversation in a quiet atmosphere. In addressing this sensitive issue, you may want to describe your view of the situation and the feelings it triggered in you:
“When you came home from the birthday party last night, I smelled alcohol and cannabis. I was really afraid to see you staggering.”
You could follow up and outline the potential effects of your daughter’s action:
«Drugs can have a strong disinhibitory effect, which means that you could do things under the influence which you would otherwise not do and which you might later regret. Moreover, drugs are not good for your health, they can be addictive and cause brain damage.»
This way you have formulated a complete I-message. Further information and exercises about I-Messages can be found here…
How could the conversation continue? You will find more tips for a constructive conversation here…